Method of making aromatic bis(ether ortho phthalic acid)s

Abstract

Aromatic bis(ether anhydride)s can be made by a nitro displacement of an N-substituted nitrophthalimide with an alkali diphenoxide to produce an intermediate aromatic bis(etherphthalimide). Hydrolysis of the aromatic bis(etherphthalimide) to the corresponding tetra-acid salt followed by acidification and dehydration, results in the production of the aromatic bis(ether anhydride). These anhydrides can be used as intermediates for making polyimides. The intermediate aromatic bis(etherphthalimide) can be employed as a plasticizer in polyimide resins.

What we claim as new and desire to secure by Letters Patent of the United States: 
     
       1. A method for making an aromatic-bis(ether dicarboxylic acid) which comprises a. effecting the nitro displacement of a nitrophthalimide of the formula, ##SPC9##    with an alkali diphenoxide of the formula,   M--O--R--O--M        to produce an intermediate aromatic-bis(etherphthalimide), (b) hydrolizing the aromatic-bis(etherphthalimide) of (a) with base to produce a tetra-carboxylic-acid-salt and (c) acidifying the tetra-carboxylic-acid salt to produce the corresponding tetra-carboxylic-acid, where R is a divalent aromatic radical having from 6-30 carbon atoms, M is an alkali metal ion, and R 1  is a monovalent organo radical selected from the class consisting of aromatic hydrocarbon radicals, halogenated aromatic hydrocarbon radicals and altyl radicals of 1--8 carbon atoms.   
     
     
       2. A method in accordance with claim 1 where the alkali diphenoxide is the diphenoxide of bisphenol-A. 
     
     
       3. A method in accordance with claim 1 where the alkali diphenoxide is the diphenoxide of hydroquinone. 
     
     
       4. A method in accordance with claim 1 where R 1  is phenyl. 
     
     
       5. A method in accordance with claim 1 where R 1  is methyl. 
     
     
       6. A method in accordance with claim 1 where M is sodium. 
     
     
       7. A method in accordance with claim 1 where N-phenyl-3-nitrophthalimide is used. 
     
     
       8. A method in accordance with claim 1 where N-phenyl-4-nitrophthalimide is used. 
     
     
       9. A method in accordance with claim 1 where a mixture of N-phenyl-3-nitrophthalimide and N-phenyl-4-nitrophthalimide is used.